Humans have a long history of having dental problems. Toothaches and the premature loss of teeth are recorded among our earliest written histories. History reflects the knowledge of the name of an Egyptian dentist who treated the Pharaoh's teeth around 3000 BC. In the early 1950's, it became known that living bone could grow and bond with certain metals such as titanium and the start of the modem use of dental implants started in earnest.
Although dental implants generally function as well as natural teeth, there are problems associated with the dental implants commonly used.
The strongest muscles in humans are known as the masseters. Masseters are located on the sides of your mouth and can exert a force of approximately 160 lbs. As such, teeth must be able to stand up to this kind of force when tearing and chewing food. Dental implants must also be able to function under this load. Implants are known to break when the force on the implanted tooth exceeds the mechanical limit of the implant material.
The stresses applied to implants during the normal course of eating include both compression as well as shear forces. Because the metal used to make implants must be machined, weaknesses are introduced into the implants that can lead to their failure. An example of a dental implant device is described in U.S. Pat. No. 5,533,898, issued to Mena, the entire contents of which are incorporated by reference herein. Replacing a broken implant is an expensive and serious undertaking. Additionally, stress can be transferred to the bone surrounding the implant causing pain, or fractures of the jaw, and bone resorption which can be even more serious than implant breakage. There is a need for a dental implant that has improved shear force resistance that is easy to machine without introducing unacceptable stress points in either the implant or the bone in which it is implanted.
Similar problems are exhibited with orthopedic implants. In particular, the compression and sheer forces placed on orthopedic implants can cause the implants to break, or cause bone resorption or procedure failure necessitating additional painful and expensive surgeries. It is therefore desirable to have an implant suitable for orthopedic use which, like the desired dental implant, has improved shear force resistance over prior art orthopedic implants and is easy to machine without introducing unacceptable stress points in either the implant or the bone in which it is implanted.